How to Use a Blockchain API Key in Postman: How Do Crypto API Keys Work?

How to Use a Blockchain API Key in Postman: How Do Crypto API Keys Work?


In this comprehensive guide, we will explore how to use a crypto API key in Postman with NOWNodes. Additionally, we learn how to get a blockchain API key with NOWNodes, how do API keys work and how to share crypto API keys securely.

Crypto API keys play a vital role in securing API access and controlling usage. If you’re building a dApp, or just need an understanding of how to use a blockchain API key in Postman for your Web3 needs, we will guide you through the process. 

First of all, to understand how to use blockchain API keys in Postman, let’s dive into the technical details and explore how do crypto API keys work.

How Do Crypto API Keys Work? 

how do api keys work

An API key is a unique string of randomly generated characters or a set of unique codes that are used to authenticate clients and grant access to an API. With crypto API key usage you can ensure that only authorized requests are made to the API, protecting sensitive data and preventing misuse.

In the context of blockchain technology and cryptocurrency exchanges, API keys play a vital role in connecting users to blockchains. The API key acts as a unique identifier that helps verify the user’s identity and grants them access to certain information or allows them to perform specific actions. This ensures that only authorized users can interact with the blockchain or exchange platform. 

There are two types of API keys: public API keys for non-sensitive data and functionality, and private API keys for accessing sensitive data. By using a crypto private API key, users can securely access their accounts, view balances, make trades, and perform other functions seamlessly.

When making a request the crypto private API key is included in the request headers or query parameters. The API server then verifies the key and grants or denies access based on its validity.

Postman provides a user-friendly interface for managing API keys. To understand how to use an API key in Postman, one must create an account with the blockchain API keys provider, copy the crypto private API key correctly, store it safely, and include it in API requests. 

Blockchain API keys are crucial tools in the world of APIs, enabling secure authentication and authorization processes. They play a significant role in verifying user identity, controlling access to sensitive data, and monitoring API activity. However, it is important to handle API keys with care, keeping them secure and implementing appropriate measures to protect against potential vulnerabilities.

Now you know how do blockchain API keys work, so let’s dive into the details and explore how to get a blockchain API key and use it in Postman with NOWNodes.

Step-by-Step Guide on How to Use a Blockchain API Key in Postman 

how to get blockchain api key

If you ever wondered how to get a blockchain API key for using it in Postman, NOWNodes offers a convenient way to access and utilize API keys for various blockchain networks and development needs. NOWNodes can provide crypto individuals and businesses with a secure and controlled environment to interact with their blockchain API services, while also ensuring efficient resource management and monitoring.

Whether it’s the Ethereum RPC endpoint, Fantom RPC endpoint, Arbitrum RPC endpoint, Solana RPC endpoint, BSC RPC endpoint, Avalanche RPC endpoint, or another, the node provider simplifies the process of interacting with these full RPC nodes, allowing developers to focus on building and scaling innovative blockchain dApps.

The node provider supports access to 84 blockchain full nodes, with additional endpoints to block explorers and WebSocket connections that can be utilized through utilizing a crypto private API key. By leveraging the NOWNodes blockchain API keys, you can retrieve real-time blockchain data, including transactions, addresses, blocks, and more.

By following a few simple steps below, you can easily get blockchain API key and start interacting with the desired network RPC nodes by utilizing the Ethereum RPC endpoint, Fantom RPC endpoint, Arbitrum RPC endpoint, Solana RPC endpoint, BSC RPC endpoint, Avalanche RPC endpoint and more.

Generate a Private API Key in NOWNodes

Blockchain API key usage starts with generating this key. Follow these steps to get your blockchain API key:

  • Navigate to the dashboard section in your account and generate a blockchain API key by pushing the button on the picture. 
  • Copy the generated API key and keep it secure. You will need it in the subsequent steps. Additionally, explore the methods for making requests in Postman.

Consider selecting a tariff plan that aligns with your requirements. You’ll find multiple options available, one of which is the START plan. The START plan is free and it allows you to access five blockchain networks through one API key and make RPC requests to the Ethereum RPC endpoint, Fantom RPC endpoint, Arbitrum RPC endpoint, Solana RPC endpoint, BSC RPC endpoint, Avalanche RPC endpoint, so on. 

In case you want to get more API keys and access all the blockchains, including a WebSocket connection, you can choose paid plans and benefit from the variety of tools for Web3 development.

When it comes to crypto private API keys, it is crucial to maintain their confidentiality and not share them with anyone, so remember not to share API keys. 

Now that you learned how to get blockchain API key with NOWNodes, it’s time to know how to use the API key in Postman. 

Use a blockchain API Key in Postman

Postman is a powerful tool that allows developers to test and integrate APIs seamlessly. If you haven’t already downloaded and installed Postman on your machine, we recommend you do it. You can also use a Web version. 

Now that you have your crypto private API key and Postman platform installed, explore the steps on how to use the API key in Postman.

Step 1: Create a New Request in Postman

In Postman, click on the “New” button to create a new request. This will open a new tab where you can configure your Postman API request. 

Step 2: Set the Request URL

In the request tab, enter the API endpoint URL provided by the NOWNodes node provider in the request URL field. Make sure to include any required query parameters. Here are the examples of Ethereum RPC endpoint, Fantom RPC endpoint, Arbitrum RPC endpoint, Solana RPC endpoint, BSC RPC endpoint, and Avalanche RPC endpoint:

Find more on the β€œNodes” page. 

Step 3: Add the Private API Key to the Request Headers

To authenticate your request, you need to add the crypto API key to the request headers. In the Headers section of the request, click on the “Add” button to create a new header. Set the key as “X-API-Key” and paste the API key you copied earlier as the value.

For example, the POST bsc_getBalance request to the BSC full node looks like

curl --location '' \
--header 'Content-Type: application/json' \
--header 'api-key: your_api_key' \
--data '{
    "jsonrpc": "2.0",
    "method": "bsc_getBalance",
    "params": [
    "id": 1

This command is used to retrieve the balance of a specific BSC address. Here are the components of the BSC RPC command:

1. curl: The command-line tool used for making HTTP requests.

2. --location: Instructs cURL to follow redirects if the API endpoint returns a redirect response.

3. '': The URL of the BSC RPC endpoint. Replace your_api_key with the actual API key provided by the NOWNodes.

4. --header 'Content-Type: application/json': Sets the request header to specify that the content type of the request is JSON.

5. --header 'api-key: your_api_key': Sets the request header to include the crypto private API key. Replace your_api_key with the private API key provided by the node provider.

6. --data: Specifies the data to be sent with the request. In this case, it is a JSON payload.

7. The JSON payload contains the following parameters:

- jsonrpc: The version of the JSON-RPC protocol being used (version 2.0).

- method: The specific method to be called (`bsc_getBalance` in this case).

- params: An array containing the BSC address for which the balance is to be retrieved and the block parameter (`latest` in this case).

- id: An identifier for the request.

This explanation of utilizing the API key will help you to authenticate your request in Postman. 

Step 4: Send the Request

Once you have set up the request URL and added the blockchain API key to the headers, click on the “Send” button to send the request to the private node through node provider NOWNodes. Postman will initiate the request and display the response received from the node provider.

Step 5: Receive the Response

Postman will show the response received from NOWNodes in the response section of the request tab. You can view the response body, headers, and other details to verify the success of your request.

As a developer, it’s essential to understand how to interpret and handle API responses effectively. Here are some tips for handling API responses in Postman:

  • Inspect the response status code to determine if the request was successful or encountered an error.
  • Check the body of the response for the data returned by the API.
  • Use Postman’s built-in features like JSON viewer to format and analyze the response data.
  • Extract relevant information from the response using Postman’s scripting capabilities.

That’s it! You have successfully used API keys in Postman with NOWNodes. Remember to keep your private API keys secure and avoid sharing them with unauthorized individuals.

How to Share Crypto API Keys Securely?

use api key in postman

When it comes to using blockchain technology, API keys play a crucial role in accessing and utilizing various blockchain platforms and services. However, sharing these private API keys securely is of utmost importance to prevent unauthorized access and potential security breaches. Here are some best practices to ensure the secure sharing of blockchain API keys.

Firstly, it is essential to encrypt the blockchain API keys before sharing them. Encryption provides an additional layer of protection by converting the API keys into an unreadable format. This ensures that even if the keys are intercepted during transmission, they cannot be easily deciphered. There are various encryption algorithms available, such as AES (Advanced Encryption Standard), that can be used to encrypt the API keys.

Secondly, it is advisable to use secure channels for sharing the API keys. Avoid sharing the keys through insecure methods such as plain text emails or messaging platforms. Instead, use encrypted communication channels such as secure file transfer protocols (SFTP) or secure email services that utilize encryption techniques like Pretty Good Privacy (PGP). These methods ensure that the API keys are protected during transit and can only be accessed by the intended recipient.

Thirdly, another important aspect is to limit the number of individuals with access to the API keys. Grant access only to those who require it for their specific tasks or responsibilities. This reduces the risk of unauthorized access and potential misuse of the API keys. Additionally, consider implementing a role-based access control system where different levels of access privileges can be assigned based on job roles and responsibilities.

Notice, that exploring the theme of how to share API keys securely is crucial to protect sensitive information and prevent unauthorized access.


Today we understand how do blockchain API keys work, how to get a blockchain API key with NOWNodes and use it in Postman, and how to share crypto API keys securely. Mastering API integration is essential for development on a blockchain, and using Postman as your development tool can significantly simplify the process.

By following the step-by-step guide on how to use a blockchain API key in Postman with NOWNodes you can easily perform API requests to RPC nodes through the Ethereum RPC endpoint, Fantom RPC endpoint, Arbitrum RPC endpoint, Solana RPC endpoint, BSC RPC endpoint, Avalanche RPC endpoint and other and retrieve data from blockchains. 

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  • How do Blockchain API Keys Work? API keys are used to authenticate clients and grant access to an API, ensuring authorized requests, protecting sensitive data, and preventing misuse in various contexts, including blockchain technology and cryptocurrency exchanges. 
  • How to use a Crypto API Key in Postman? Get a blockchain API key on the NOWNodes website, choose the method, include the crypto private API key in requests, send the API request, and receive the response in Postman.
  • How to Share Blockchain API Keys Securely? Following best practices such as encrypting the keys, and using secure communication channels, limiting access, organizations can ensure the safe and secure sharing of these valuable assets.